1. Field of the Invention
The present invention relates to electronic equipment having a cooling device circulating a cooling fluid.
2. Description of the Related Art
Electronic equipment includes mainframe computers and medium-scale server computers used by corporates such as banks, in addition to widely used personal computers and desk-top computers.
Server computers as electronic equipment are typically connected to a plurality of terminals. Such electronic equipment is formed of a plurality of stacked electronic devices, which run software programs for calculation or retrieving mail data.
Depending on the purposes of applications, the user must replace, add, or remove the electronic devices, each running the software program of its own.
The electronic equipment must be continuously powered 24 hours a day because the electronic equipment is constantly accessed by any of the terminals.
Each electronic device typically includes a sub-cooling unit in addition to a main-cooling unit. In the case of a failure of the main-cooling unit, an alarm alerting the user to the failure is triggered. The sub-cooling unit cools the electronic device until the main-cooling unit is restored.
Such cooling devices of the electronic equipment typically employ fans.
In step with the latest high processing speed and large memory capacity, semiconductor devices such as central processing units (CPUs) rise high in temperature to the degree with which a cooling device using a fan has difficulty. If cooling efficiency is increased, a noise problem due to high speed rotation of the fan arises. The cooling device using a cooling fluid circulation, once used in the mainframe computer field, is now reviewed.
Under these situations, a cooling device of the conventional art using a cooling fluid circulation is now studied from safety and reliability considerations.
For example, Japanese Unexamined Patent Application Publication No. 6-97338 discloses a fluid circulating type cooling device of a mainframe computer. In the disclosure, many wiring boards, each having a semiconductor device generating heat, are stacked in a casing of electronic equipment. A flat header is attached to the semiconductor. A cooling fluid is circulated in a flexible tube routed between the heat generator and a heat exchanger, thereby cooling the heat generator.
Japanese Unexamined Patent Application Publication No. 5-142886 discloses a notebook computer having a cooling device using a cooling fluid circulation. In the disclosure, a highly reliable and high-performance cooling device is used for a mobile electronic apparatus such as a notebook computer. A flexible heat transport device having a heat receiving header, a heat dissipating header, and a flexible tube is used in the cooling device.
In accordance with the conventional art described in the above disclosures, a cooling fluid, running through a flexible tube routed on a wiring board having heat generating electronic components, circulates between heat generating elements and a heat exchanger. No sufficient consideration is given to the loading and unloading of the wiring board.
When a wiring board having heat generating electronic components is loaded in a casing of electronic equipment, thermal coupling to a heat sink path (a cooling fluid piping) of the heat generating electronic components must be easily established in addition to electrical connection. There is no mention of such a structure satisfying this requirement in the above disclosures. The server in a network system has difficulty in the removal of a wiring board in need of replacement and the loading of another wiring board with safety in the casing particularly in the middle of operation of the electronic apparatus. In such electronic equipment, a new electronic module as a wiring board having heat generating electronic components must be occasionally added.
If a wiring board mounted in the electronic apparatus or a component in a cooling fluid circulation system fails, the wiring board or the component must be replaced. However, the above conventional arts provide no mechanism appropriate for allowing a corrective action to take without stopping the operation of the system.
If the fluid circulation type cooling device is attached to each electronic apparatus, the cooling device may be duplicated, such as a safety mechanism using a fan.
The duplication of the fluid circulation type cooling device in each electronic apparatus raises space and cost problems.